Conventionally, a rotating tool such as a face mill cutter, an end mill or the like, particularly a throw away type rolling tool structured such that a cutting insert is installed to a holder has been in heavy usage in terms of an economical efficiency.
A great load is applied to a rolling tool having a long cutting edge at a time of cutting. Accordingly, a cutting insert in which a cutting resistance applied at a time of cutting is reduced has been proposed.
For example, in patent document 1, there is disclosed a cutting insert provided with a cutting edge which is positioned on an intersection of an upper surface and a side surface, and a groove portion which is provided on the side surface in such a manner as to divide the cutting edge. In accordance with the structure mentioned above, a chip is divided finely in a width direction, and a cutting resistance applied at a time of cutting is reduced.
However, in the cutting insert, a plurality of chips divided finely in the width direction are generated, and there is a risk that a plurality of chips come into collision with each other. Accordingly, there has been demanded a structure which has an excellent chip discharging property as well as reducing a cutting resistance.